System Rules 更好的测试

1:编写测试事例时候,我们要从控制台拿到数据与断言进行对比,通常要编写jdk 标准输出的屏蔽控制器.文章标题的包,能够更好的为我们进行工作.

package demo2;

import static org.junit.Assert.assertEquals;

import org.junit.Rule;
import org.junit.Test;
import org.junit.contrib.java.lang.system.StandardOutputStreamLog;
import org.junit.contrib.java.lang.system.SystemErrRule;
import org.junit.contrib.java.lang.system.SystemOutRule;

public class demo1 {
    
    @Rule // 过去写法
    private final StandardOutputStreamLog log=new StandardOutputStreamLog();
    
    //正确输出
    @Rule 
    private final SystemOutRule sRule=new SystemOutRule();
    
    //错误输出
    @Rule
    private final SystemErrRule errrule=new SystemErrRule();
    
    @Test
    public void miantest() {
        sysou();
        assertEquals(2, sRule.getLog());
    }

    private void sysou() {
        System.out.println(2);
    }

}

其实使用事例介绍

Clear Properties

public class MyTest {
    @Rule
    public final ClearSystemProperties myPropertyIsCleared
     = new ClearSystemProperties("MyProperty");

    @Test
    public void overrideProperty() {
        assertNull(System.getProperty("MyProperty"));
    }
}

Provide Properties

public class MyTest {
    @Rule
    public final ProvideSystemProperty myPropertyHasMyValue
     = new ProvideSystemProperty("MyProperty", "MyValue");

    @Rule
    public final ProvideSystemProperty otherPropertyIsMissing
     = new ProvideSystemProperty("OtherProperty", null);

    @Test
    public void overrideProperty() {
        assertEquals("MyValue", System.getProperty("MyProperty"));
        assertNull(System.getProperty("OtherProperty"));
    }
}